1. Field of the Invention
The present invention relates to devices for facilitating the connection of vehicles by registering and conveying information to an operator of one vehicle as to their changing positional relationship as the operator directs his vehicle along a path intended to bring hitches on the two vehicles into position for inter-engagement.
2. Description of the Prior Art
The increasing use of trailers, both in the commercial trucking industry and in the recreational and house trailer fields, has led to the development of a number of devices for facilitating the connection of a towing vehicle with a trailer. The need for such devices arises from the difficulty encountered in backing the towing vehicle into such a position with respect to the trailer that the hitches on the vehicles, the relative positions of which are concealed from the operator by the vehicle body, are positioned for inter-engagement.
One example of such a device is disclosed in the United States patent to Salmi, U.S. Pat. No. 3,734,539, in which a retractable guide line extends between the trailer and the towing vehicle and its deflections and its extension and retraction produce non-proportional signals purporting to enable the operator of the towing vehicle to direct it in the proper way to effect positioning of the hitches of the two vehicles for inter-engagement. The Salmi sensing device must, however, have its initial positioning changed, and the position of his guide line also must be changed, if the trailer is to be approached by the towing vehicle from different directions. Furthermore, it indicates only whether the angular error in the approach is to the right or left without indicating its magnitude. The operator thus is not informed as to the magnitude of the course correction required. Also, Salmi's means for indicating the approach of the towing vehicle's hitch to that of the trailer gives only "Caution" and "Stop" signals without indicating the magnitude of the distance between the hitches.
Another example of such a device is disclosed in the United States patent to Thompson, U.S. Pat. No. 2,736,885, in which deflections of a similar guide line extensible between the trailer and an unspecified point on the towing vehicle are caused to rock an arm pivoted on an axis located to one side of a line connecting the trailer and towing vehicle hitches and thus to mechanically deflect an angle indicator mounted on the trailer in a position to be viewed through the rear window of the towing vehicle. A light signal indicates contact between the portion of the device mounted on the towing vehicle and that mounted on the trailer. Because of the unspecified positioning of the guide line anchor on the towing vehicle and the positioning of the rockable arm pivot to the side of the trailer hitch, it appears that only approximate hitch alignment could be achieved with the Thompson device even in a straight-line approach and that hitch alignment would be impossible if it were necessary for the towing vehicle to approach the trailer at a substantial angle.
The primary object of the present invention is to remedy such deficiencies in the prior art devices. Thus, it is an object to provide a towing hitch alignment director which will quantitatively indicate departures in either direction from the selected angle of approach to a trailer by a towing vehicle, without any need for repositioning or adjustment of any portion of the director if the trailer is to be approached from other than a single predetermined direction. It is a further object to provide a director which will quantitatively and continuously indicate the distance between the hitch of one vehicle and that of another as they are moved toward each other. A further object is to provide for automatic scale expansion of the distance indication as the distance between the two vehicle hitches shortens.